Benford’s law is a statement that for a set of numbers the first (or leading) digit of each number is not evenly distributed.
Instead, there is a 30.1% chance of finding the digit ‘1’ in the numbers as a first digit. This probability is three times higher
than that of the uniform or random distribution. This seems to be rather counter-intuitive. This law is named after Frank
Benford [1], who in 1938 published that the law appeared in many sets of numbers, from the surface areas of rivers to
baseball statistics to figures picked from newspapers. However, it had actually been found by Newcomb [2] in 1881. More
recently, it is shown [3,4] that the probability is scale-invariant, which means that upon changing the unit or the scale of
numbers in the set, for example from meters to feet, the set still follows the law. Furthermore, it can be used [5,6] to detect
cases of possible number fraud, such as in lists of numbers from taxes, voters and even digital images.
It is important to know whether simulation values follow Benford’s law, because it can be used to test the validity
of algorithms employed in the simulations. It is already known [7] that in equilibrium molecular dynamics simulations,
the coordinates of the molecules apparently follow Benford’s law under periodic boundary condition. However, in a nonequilibrium
system, like droplet collisions, it is not yet examined at all. Here, we extend an application of the law to the
non-equilibrium situation. We also consider not only coordinates but also combinations of other physical quantities, such
as velocities or forces. We will show that the law actually also holds more accurately than previous results [7], where it
was compared with a uniform distribution, and furthermore can be used to understand non-equilibrium processes from a
different perspective.
We will first present a relevant